In a conventional glass melter, burners are located above the surface of glass materials in the melter (e.g., the glass batch materials and later the melted glass materials, or collectively the “glass melt”) and are directed downwardly toward the top surface of glass melt. In an effort to increase the thermal efficiency of glass melters, burners may also be located below the surface of the glass melt and fired up into the glass melt in what has been referred to as submerged combustion melting or a submerged combustion melter (SCM).
FIG. 1 is a schematic illustration of a conventional SCM apparatus 71 having a melting chamber 72 containing a molten pool of glass melt 74. With reference to FIG. 1, the melting chamber 72 includes a feed port 76 for feeding glass batch material from a hopper 75 into the melting chamber 72. The batch material may be provided in liquefied, granular or powdered form. The melting chamber 72 also includes an exhaust port 78 through which exhaust gases may escape the melting chamber 72. The melting apparatus 71 also includes a conditioning chamber 80 connected to the melting chamber 72 by an outlet or flow passage 82. Molten material from the molten pool 74 flows from the melting chamber 72 to the conditioning chamber 80 through the flow passage 82 and then exits the melting apparatus 71. One or more orifices 86 may be formed in the bottom wall 88 of the melting chamber 72 whereby burners 10 inject flames into the molten pool of glass melt 74. In alternative arrangements, the orifices 86 may be provided in one or more side wall 90 of the melting chamber 72 and/or may be perpendicular or slanted relative to the wall of the melting chamber 72.
In an SCM apparatus the flame and products of the combustion (e.g., carbon dioxide and water, to name a few) travel through and directly contact the glass melt transferring heat directly to the glass melt and resulting in a more efficient heat transfer to the glass melt than in conventional glass melters. More of the energy from the combustion may be transferred to the glass melt in an SCM apparatus than in a conventional glass melter. Further, the flame and products of the combustion travelling through the glass melt in an SCM apparatus may also agitate and mix the glass melt, thereby enabling the glass melt to be mixed without use of mechanical mixers typically required in conventional glass melters. The glass melt in a conventional glass melter is also not significantly stirred by the presence of the burner and flame above the surface of the glass material without the aid of mechanical mixers, such as mixing blades. Use of such mechanical mixers in conventional glass melters is problematic. For example, as a result of high temperatures in and the corrosive nature of the glass melt, mechanical mixers in glass melters possess a short useful life and replacement thereof is expensive. As a mechanical mixer in a conventional glass melter degrades, material from the mixer may contaminate the glass melt.